Method for making light emitting diode

Abstract

An exemplary light emitting diode ( 30 ) includes a light output unit ( 31 ), an optical lens ( 33 ) and a reflective film ( 35 ). The optical lens includes a light input surface ( 331 ) facing the light output unit, a top interface ( 333 ) opposite to the light input surface, and a light output surface ( 335 ) between the light input surface and the top interface. The reflective film is integrally formed on and in immediate contact with the top interface of the optical lens. The reflective film is made of a transparent resin matrix material dispersed with a plurality of reflective particles. A method for making the light emitting diode is also provided.

1. A method for making a light emitting diode, comprising the steps of:
 mixing a plurality of reflective particles into a plurality of transparent resin particles to attain a raw material; 
 heating and melting the raw material to form a molten reflective material; and 
 providing a multi-shot injection mold having a first shot cavity for receiving the molten reflective material and a second shot cavity for receiving molten transparent resin material; 
 injection molding the molten reflective material and the molten transparent resin material to produce an optical lens made of transparent resin derived from the molten transparent resin material and having a reflective film derived from the molten reflective material, the optical lens defining a light input surface, a top interface opposite to the light input surface, and a light output surface between the light input surface and the top interface, the reflective film being formed in immediate contact with the top interface; and 
 coupling the optical lens to a light output unit to form a light emitting diode, the light input surface of the optical lens facing the light output unit. 
 
   
   
     2. The method according to  claim 1 , wherein a refractive index of the reflective particles is in the range from about 1.6 to about 2.75. 
   
   
     3. The method according to  claim 2 , wherein the reflective particles are selected from the group consisting of titanium dioxide particles, barium sulfate particles, zinc sulfide particles, zinc oxide particles, antimony oxide particles, calcium carbonate particles and any combination thereof. 
   
   
     4. The method according to  claim 1 , wherein an outer surface of the reflective film distal from the optical lens is one of a flat surface, a spherical-shaped surface, and a funnel-shaped surface. 
   
   
     5. The method according to  claim 1 , wherein the light emitting diode defines a central vertical axis that passes through centers of the light output unit and the optical lens, and the light input surface of the optical lens has an inverted U-shaped cross-section taken along a plane passing through the central axis. 
   
   
     6. The method according to  claim 1 , wherein the top interface is a funnel-shaped. 
   
   
     7. The method according to  claim 1 , wherein the light output surface comprises a first refractive surface having the shape of a periphery of a frustum, and a second refractive surface adjacent to the first refractive surface, and the second refractive surface has the shape of an outer portion of a flat-topped dome.